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Proteins Produced by Fat May Be Cause of Increased
Heart Disease Risk
Study of older women part of new view of fat as an
“organ” affecting health
 March
28, 2005 - The war against obesity got a new boost today with the
release of study of older women claiming inflammatory proteins produced
by fat may be linked to increased risk for heart disease – America’s
number one killer. The research is based on a new idea in medicine –
that fat is an “organ” that produces proteins and hormones that affect
metabolism and health.
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Are You Too Fat? |
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The definition of an obese person is one
with a body mass index, or BMI, of 30 or higher. A BMI under
18.5 is "underweight," 18.5 to 24.9 2 is normal, 25 to 29.9 is
overweight.
The National Institutes of Health provides a
quick BMI calculator -
Click Here |
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March 17, 2005 – If the age of life expectancy
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Read more...
Obesity & Life Expectancy
Government statistics indicate that growing
numbers of Americans are seriously overweight, and new research
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could reverse a decades-long trend of improved life expectancy.
By Art Chimes,
Voice of America -
Click Here |
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“It is well known that obesity affects nearly
one-third of adults in the United States and is closely linked with
heart disease,” said Tongjian You, Ph.D., instructor in geriatric
medicine at Wake Forest University Baptist Medical Center and lead
author. “While we don’t fully understand the link between obesity and
heart disease, our study suggests that inflammatory proteins produced by
fat itself may play a role.”
The study, to be published in the April issue of
the American Journal of Physiology – Endocrinology and Metabolism,
evaluated whether inflammatory proteins produced by fat are linked to
risk factors for heart disease, including high blood pressure, high
cholesterol and how the body responds to insulin.
The researchers studied two proteins that promote
inflammation (interleukin 6 and tumor necrosis factor alpha) and a
protein that promotes blood clots (plasminogen activator inhibitor 1).
These proteins are all manufactured by fat tissue and involved in
atherosclerosis, the buildup of fatty deposits in the linings of blood
vessels. In addition, the scientists also looked at two “good” proteins,
leptin, which regulates energy metabolism, and adiponectin, which has
anti-inflammatory effects.
To gauge production levels of the proteins, the
scientists took small samples of subcutaneous fat, which is just under
the skin, from the abdomen and measured levels of messenger RNA (mRNA),
which carries the genetic code instructions for cells to create the
proteins.
The study included 20 post-menopausal women from 50
to 70 years old who were overweight or obese and had waists larger than
35 inches. Women in this age group are at increased risk for metabolic
syndrome, a cluster of symptoms that increases the risk for heart
disease. The syndrome is diagnosed when someone has at least three of
the following: abdominal obesity, high triglycerides, low levels of
high-density liprorotein (“good”) cholesterol, high blood pressure and
increased levels of glucose (sugar) in the blood.
In 15 study participants without diabetes, higher
levels of the “bad” proteins, interleukin 6 and tumor necrosis factor
alpha, were associated with a lower ability to respond to insulin and
use glucose. On the other hand, higher levels of the “good” protein
adiponectin were associated with an increased ability to use glucose.
Eight women who were diagnosed with metabolic syndrome – and had
multiple risk factors for heart disease – had levels of adiponectin that
were 32 percent lower than the 12 women who didn’t have the disorder.
“This suggests that low production of adiponectin
in subcutaneous fat is linked with an elevated risk of heart disease,”
said You.
The findings are significant because of the
prevalence of both heart disease and obesity in the United States. Heart
disease is the No. 1 killer in the United States, causing about 79,000
more deaths per year than the next five leading causes of death
combined.
“It’s possible that modifying the inflammatory
proteins through medication could also lower the risk of heart disease,”
said Barbara Nicklas, Ph.D., senior researcher and an associate
professor of internal medicine. “The findings point to a possible
treatment target for new drugs. Our goal is to learn more about how
these proteins are produced and how levels can be changed.”
Nicklas and colleagues have already begun a study
to test whether diet and exercise will affects levels of the proteins.
Scientists already know that weight loss and physical activity can
reduce inflammation, but don’t know if this happens because the
production of inflammatory proteins by fat tissue is reduced.
“We need to understand more about the mechanism,”
Nicklas said.
The research was supported by the National
Institutes of Health, the Wake Forest University Claude D. Pepper Older
Americans Independence Center and the Wake Forest University General
Clinical Research Center. Other researchers were Rongze Yang, Ph.D., and
Dawei Gong, from the University of Maryland School of Medicine, and Mary
Lyles, M.D., from Wake Forest Baptist.
About Wake Forest University Baptist Medical
Center: Wake Forest Baptist is an academic health system comprised of
North Carolina Baptist Hospital and Wake Forest University Health
Sciences, which operates the university’s School of Medicine. The system
comprises 1,282 acute care, psychiatric, rehabilitation and long-term
care beds and is consistently ranked as one of “America’s Best
Hospitals” by U.S. News & World Report.
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